Fix typo in c2.6 of the English version

en/02.6.md

@@ -333,7 +333,7 @@ We can see that the source file in `container/heap` has the following definition
 	type Interface interface {
 	    	sort.Interface // embedded sort.Interface
 	    	Push(x interface{}) //a Push method to push elements into the heap
-	    	Pop() interface{} //a Pop elements that pops elements from the heap
+	    	Pop() interface{} //a Pop method that pops elements from the heap
 	}
 
 We see that `sort.Interface` is an embedded interface, so the above Interface has the three methods contained within the `sort.Interface` implicitly.